The present invention pertains to cellular communication systems and more particularly to efficiently using an allocated shared channel resource in the cellular communication system.
Modern cellular telecommunication systems include mobile users, base stations, mobile switching centers (MSC), and message distribution centers (MDC). A base station includes a base station transceiver and a base station unit. In CDMA (Code Division Multiple Access) systems, multiple base station transceivers may be in communication with each particular mobile unit. Therefore, each mobile unit may have several links from the telecommunication equipment to it in the communication mode at a single time. One of these links will be designated primary. As can be seen, there is much equipment associated with a modern cellular communication link or channel. Since data as well as voice type communications are desirable by mobile telecommunication users, high data rate resources are installed within the telecommunication system.
These high data rate resources are supplemental forward and reverse channels with a capability to transmit far in excess of current voice channel limitations. Such high data rate equipment, and the radio spectrum and/or power consumed, is by nature expensive. Therefore, this equipment and system resources must be shared in order to provide economical services to many mobile units.
Each channel has a number of time slices which make up the channel and may operate at various transmission rates. Typically mobile units request when connecting to the system the highest rate possible that they can handle. To fulfill this request the base station presently considers the user's subscribed rate, previously allocated channels and the current message flow backlog.
This base station scheme does not work well for transmission control protocol (TCP) flows and yields a significantly lower throughput. The present scheme yields varying requested rates which cause TCP to react to the varying bandwidths by substantially reducing throughput.
Further, the base station transceiver typically searches for the highest channel rate available up to the requested rate by the mobile unit. If for any reason the base station transceiver (BTS) cannot provide this highest channel rate, the BTS will then search for the next lower rate beginning with the earliest available time slot (time slice). This process continues until a success is found or the searching is exhausted and therefore the request is denied.
Further complicating matters, since CDMA systems typically have several links to the mobile unit, this process must be repeated and negotiated to find a common rate and time slice among the several base station transceivers involved with the mobile unit. Therefore, again subscriber throughput may be severely impacted due to limitations with the weakest or most congested base station.
Accordingly it is highly desirable to have methodology for efficient selection of rates and time slot assignments within the base station to substantially increase system throughput.